The first man Adam became a living being. The last Adam became a life-giving spirit. I Corinthians 15.45

Understanding:

The first Adam, a living being, refers to being a hostage of the flesh and sinful nature.

The last Adam, Jesus Christ, refers to the Person born of the Holy Spirit. This is, the Divine Being, who, though a Man, did not submit to the flesh and sinful nature. Instead, He remained subject to the Voice of the Spirit and never disobeyed it.

Therefore, we can conclude that as long as a Christian does not have his human nature transformed into a spiritual nature, he has not been born of the Spirit.

Only those who are born of the Holy Spirit are spirit. This is, they have obtained His nature.